The paper describes the research approach for defining a new set of best practices for IT Outsourcing (ITO) that will help the Swedish global companies to improve their ITO performance. To define this new set of best practices we have investigated the practices used by two Swedish global companies and compared with those recommendations gathered in a review of IT outsourcing literature. As we have seen till now the best practices for IT outsourcing are underrepresented in the research literature. However, they are fairly well represented in the ITO practitioners’ world. From the ITO research literature, we have selected 88 best practices, compiled and reduced them to 19 by eliminating the duplicates and removing those that are not exclusively related to ITO. Furthermore, we have asked the companies part of our case study about their opinion about these 19 best practices, if and how they have implemented them. The results of this research have shown that 60% of the best practices are accepted and are/or planned to be practiced by these global companies. Furthermore, we have found a new best practice that has not been mentioned in the research literature and which the companies from our case study recommended as very important. Moreover the results of our research show that 25% of the best practices are rejected by these global companies and we argue that the reason for this high discrepancy is “The buyer-seller dilemma”. The rest of the examined best practices, 15%, are partly accepted. Finally, our list of best practices consists of 15 items after removing those that have been rejected but including the partly accepted ones.